It is one of America’s most majestic and recognizable landmarks, having beckoned Teddy Roosevelt, Ansel Adams and, more recently, protesters.

From the granite walls of El Capitan in California’s Yosemite National Park, demonstrators have draped large flags and banners several times in the past year in protest of a number of issues, including the Israel-Hamas war and various Trump administration policies.

There was one symbolizing transgender pride, another saying “Stop the Genocide” and an upside-down American flag, which represents distress.

Now, the federal government seemingly wants to keep the famous rock formation a blank slate. It has outlawed large flags, banners and signs from El Capitan and most of the park altogether.

The ban appears to have been formalized last month by Yosemite’s acting superintendent, Raymond McPadden, in a Park Service compendium of regulations dated May 20.

The rule tracks with a series of punitive actions by the Trump administration against some critics of its immigration policies and Palestinian sympathizers.

Violators could face up to six months in jail and a fine of up to $5,000 for individuals and $10,000 for groups — penalties already in place for various offenses in the park.

“This restriction is necessary to preserve the values of wilderness character in accordance with the Wilderness Act, provide for an unimpaired visitor experience, protect natural and cultural resources in designated Wilderness and Potential Wilderness Addition portions of the park,” Mr. McPadden wrote.

Parks officials also cast the display of large flags — those greater than 3 feet by 5 feet — on any of the cliffs or mountains in Yosemite as a potential safety hazard that they said could interfere with climbing activity. Flags larger than that size would require a permit.

The Park Service did not immediately respond to a request for comment on Tuesday about the new rule, which was reported earlier by Climbing magazine and SFGate.com. Nor did the White House.

Miranda Oakley, 40, one of four climbers who unfurled a 25-by-10-foot banner last June with the colors of the Palestinian flag saying “Stop the Genocide,” said in an interview on Tuesday that the Trump administration was further trying to suppress voices of dissent.

“To me, it still seems like they want to control what we’re saying,” said Ms. Oakley, who is part of the group Climbers for Palestine.

Ms. Oakley wondered what would happen to people who don’t cooperate with the new rule.

“Are they going to detain them indefinitely, as they have for some international students that have spoken out for Palestine?” she asked.

In February, a small group of protesters hung an inverted American flag — a signal for distress that began with sailors — off the side of El Capitan to protest the Trump administration’s cuts to the Park Service.

Plenty of eyes were already fixated on El Capitan for the annual phenomenon known as firefall, when the light from the setting sun causes a seasonal waterfall to glow orange.

The display occurred shortly after at least 1,000 Park Service employees were abruptly dismissed from their jobs, part of a sweeping federal work force downsizing initiative that was once overseen by President Trump’s now-estranged ally, Elon Musk.

An additional 3,000 people were fired from the U.S. Forest Service, which plays a significant supporting role with the parks.

In May, a group of climbers unfurled a transgender pride flag in the middle of El Capitan to criticize the Trump administration’s rollback of protections for L.G.B.T.Q. people, including its elimination of diversity, equity and inclusion programs, The San Francisco Chronicle reported.

On the same day last month that the compendium was issued, Doug Burgum, the interior secretary, whose agency oversees the Park Service, asked the public to take note of any signs at parks or on public lands that “are negative about either past or living Americans.” In a directive, Mr. Burgum said that he was carrying out the provisions of an executive order signed by President Trump for “Restoring Truth and Sanity to American History.”

El Capitan had a starring role in “Free Solo,” the Oscar-winning 2018 documentary about the climber Alex Honnold’s quest to reach the top of the landmark without a rope.

Ms. Oakley, who estimated that she had climbed El Capitan more than 20 times, said the cliff is a statement in its own right, especially when driving into Yosemite Valley.

“It is right smack dab in your face,” she said.